Why does the computer mess up ur eyes?

    computer the long to is it are thats things this
    
Why does the computer mess up ur eyes?
every one always says staring atthe computer all day will ruin ur eyes but y what is it thats different about the computer?
i wondered this myself and looked into it, when you stare at something thats close for long periods of time, a computer screen or reading etc, the lens inside your eye is staying on that fat shape (which allows focus on near objects) for a long period of time, doing this a lot will make the lens have trouble changing back to its thin shape (which allows long distance vision) so things that are far away are blurry.

This has happened to me and now i need glasses to see things far away. :[